SME-08B20

Optical Encoder IC

1. OVERVIEWThe SME-08B20 is a 3-channel optical encoder IC with analog and digital signal output.
The SME-08B20 consists of an LED and an OEIC (Opto-Electric Integrated Circuit) in a single package.
The light emitted from the LED is projected onto the code wheel, and the reflected light is received by a photodiodeto detect the relative movement between the SME-08B20 and the code wheel. In addition, Z-phase, the origin signal,
is output by setting a pattern on the code wheel for origin detection.

2. FEATURES◼
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Compact clear molded package (L=3.95mm W=3.4mm H=1.0 mm)
80µm resolution
LED and OEIC fabricated in a single package
3-channel signal output
4.5 to 5.5 V supply voltage
27mA current consumption
LED wavelength: 850nm

3. BLOCK DIAGRAM
VDD_D

VDD_A

PD array for incremental/Z- phase
LEDIV Convertor

Amplifier

LEDDriver
CHZ
CHBB
CHB
CHAB
CHA

VSS_D

SME-08B20 Data Sheet
Preliminary-DE240070-E001

VSS_A

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SME-08B20

Optical Encoder IC

4. PIN LAYOUT

CH A

VDD_D

VDD_A8716VSS_A

5CHAB

9CH B

2VSS_D
34CH ZCHBBTop View

5. PIN DESCRIPTION
No.

Name

I/O

1CHAO

A-phase analog signal (A phase) output

2CHB

O

B-phase analog signal (B phase) output

3CHZ

O

Z-phase digital signal output

4CHBB

O

B-phase inverting analog signal (BB phase) output

5CHABO

A-phase inverting analog signal (AB phase) output

6

VSS_A

-Ground7

VDD_A-

Supply voltage

8

VDD_D

-

Supply voltage

9

VSS_D
I/O type I: Input

SME-08B20 Data Sheet
Preliminary-DE240070-E001

Function

GroundO: Output

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Optical Encoder IC

6. ABSOLUTE MAXIMUM RATINGS
Parameter

SymbolConditions

Supply voltage

VDD

VDD_A, VDD_D pins

Output voltage

VOUT

CHA, CHB, CHAB, CHBB, CHZ pins

Storage temperature

TSTG

RatingUnit

note-0.3 to 7.0

V*1-0.3 to VDD+0.3

V*1,*2-40 to 85℃*3*1: Parameters must not exceed ratings, not even momentarily. If a rating is exceeded, there is a risk of IC failure,
deterioration in characteristics, and decrease in reliability.
*2: VDD in absolute value ratings refers to the recommended operating voltage VDD value.
*3: Stored separately in Nitrogen (N2) atmosphere or vacuum.

7. RECOMMENDED OPERATING CONDITIONS
VSS=0V codewheel ROP:11mm
Parameter

SymbolConditions

MIN

TYP

MAX

Unit

Supply voltage

VDD

Between VDD and VSS terminals
VDD_A=VDD_D
VSS_A=VSS_D

4.555.5

V

Operating temperature

Ta--40-85°C

Code wheel radial misalignment

ER-0.2+0.2mm

Code wheel tangential misalignment

ET-0.2+0.2mm

Code wheel GapG0.51.0mm

0.75* Operation outside the recommended operating conditions may adversely affect reliability. Use only within
specified ratings

8. ELECTRIC CHARACTERISTIC
8.1. DC Characteristics
VSS=0V、Ta=25C
Parameter

SymbolConditions

MIN

TYP

MAX

Unit

Current consumption

IDD1

Include LED load current
At no output load

-2740mA

Output signal amplitude

VPP

0.91

1.1

VPP

Output signal offset voltage

VOFFSET

0.45VDD

0.5VDD

0.55VDDV

Reference voltage

VREF

0.5VDD

V*Under our installation conditions and typical recommended operating conditions

SME-08B20 Data Sheet
Preliminary-DE240070-E001

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SME-08B20

Optical Encoder IC

8.2. AC Characteristics
VSS=0V、Ta=25C
Parameter

SymbolOutput frequency

FOUT

Output stable latency

twaitConditions

MIN

TYP

1-MAX

Unit

120

KHz

-ms

*Under our installation conditions and typical recommended operating conditions

9. FUNCTIONAL DESCRIPTION
The light emitted from the LED is projected onto the code wheel, and the reflected light is received by a photodiodeto detect the relative movement between the SME-08B20 and the code wheel. In addition, Z-phase, the origin signal,
is output by setting a pattern on the code wheel for origin detection.

9.1. LED Auto Power Control (APC) Brightness Adjustment Function
The SME-08B20 has a built-in automatic LED brightness adjustment function (Auto Power Control) to compensate
for LED brightness variations and temperature fluctuations.

SME-08B20 Data Sheet
Preliminary-DE240070-E001

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SME-08B20

Optical Encoder IC

10. TIMING DIAGLAM

Direction of code wheel rotation: CCW

Parameter Definition
Parameter
Output signal amplitude
Output signal offset voltage
Maximum (Minimum) outputsignal amplitude voltage
Output signal crosspoint voltage

Symbol
VPP ,VPPA ,VPPB
VOFFSETVOFFSETA,OFFSETB

Peak to peak signal amplitude in voltage
Offset voltage of output signal (center voltage)

VPA,VPB,VMA,VMB

Peak and bottom of output signal amplitude

VX12,VX34,VX56,VX78

Voltage at which CHA signal crosses CHB or CHBB

Encoder Output Characteristics

Code wheel: ROP = 11mm

Parameter

SymbolMIN

Z-phase pulse width

PZS
SX-TYP

430±8State error±5P±12Pulse width error
PX±5*Under our installation conditions and typical recommended operating conditions

SME-08B20 Data Sheet
Preliminary-DE240070-E001

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Optical Encoder IC

11. RECOMMENDED CODE WHEEL CONDITIONSParameter
Pattern width ratio (reflective/non-reflective)
Incremental pattern cycle
Incremental pattern width
Pattern length
Reflectance (reflective part)
Reflectance (non-reflective part)

Symbol
WW/WB
PPWW,WB
LW
RFMin
(0.9)
TBD
TBD
1.860-Typ180
40-Max(1.1)
TBD
TBD
10UnitNoteμmμmmm%%

ROP=(PPR*PP)/2

unit:mm

SME-08B20 Data Sheet
Preliminary-DE240070-E001

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Optical Encoder IC

12. CODE WHEEL MOUNTING CONDITIONS
The optical center of the encoder IC should be aligned with the ROP.
Please evaluate the mounting conditions thoroughly before setting the encoder IC.

13. TYPICAL APPLICATIONS

SME-08B20 Data Sheet
Preliminary-DE240070-E001

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SME-08B20

Optical Encoder IC

14. PACKAGING DIMENSIONSTopview
光学中心3.40±0.20

2.62

3.95±0.20

0.50

Sideview2

1.00±0.1

0.52

Sideview18×0.45

Bottomview
8×0.35

2.15

0.90

0.90

0.50

0.95

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Preliminary-DE240070-E001

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Optical Encoder IC

15. USAGE AND PRECAUTIONSThis product is designed and manufactured to the generally accepted standards of reliability as expected for use ingeneral electronic and electrical equipment, such as personal equipment, machine tools, and measurement
equipment. This product is not designed and manufactured to be used in any other special equipment requiringextremely high level of reliability and safety, such as aerospace equipment, nuclear power control equipment, medicalequipment, transportation equipment, disaster prevention equipment, security equipment.
If you wish to use this product in equipment requiring extremely high level of reliability, please contact our sales
department or representative in advance.
In the event that this product is used in such equipment, please take scrupulous care and apply fail-safe techniques
including redundancy and malfunction prevention in order to prevent damage to life, health, property, or infrastructureetc. in case there is some malfunction in the product.

Please pay your attention to the following points at time of using the products shown in this document.
1. The products shown in this document (hereinafter ”Products”) are designed and manufactured to the generally
accepted standards of reliability as expected for use in general electronic and electrical equipment, such as
personal equipment, machine tools and measurement equipment. The Products are not designed and manufactured
to be used in any other special equipment requiring extremely high level of reliability and safety, such as aerospaceequipment, nuclear power control equipment, medical equipment, transportation equipment, disaster prevention
equipment, security equipment. The Products are not designed and manufactured to be used for the apparatus thatexerts harmful influence on the human lives due to the defects, failure or malfunction of the Products.
If you wish to use the Products in that apparatus, please contact our sales section in advance.
In the event that the Products are used in such apparatus without our prior approval, we assume no responsibility
whatsoever for any damages resulting from the use of that apparatus.
2. NPC reserves the right to change the specifications of the Products in order to improve the characteristics orreliability thereof.
3. The information described in this document is presented only as a guide for using the Products. No responsibility isassumed by us for any infringements of patents or other rights of the third parties which may result from its use. No
license is granted by implication or otherwise under any patents or other rights of the third parties. Then, we assume
no responsibility whatsoever for any damages resulting from that infringements.
4. The constant of each circuit shown in this document is described as an example, and it is not guaranteed about its
value of the mass production products.
5. In the case of that the Products in this document falls under the foreign exchange and foreign trade control law orother applicable laws and regulations, approval of the export to be based on those laws and regulations are necessary.
Customers are requested appropriately take steps to obtain required permissions or approvals from appropriate
government agencies.
6. When exporting customer’s products that use the Products, customers must comply with the "Foreign Exchange andForeign Trade Act" and other export-related laws and regulations, and follow the necessary procedures inaccordance with those laws and regulations. Do not use the Products in equipment whose sale is prohibited byexport-related laws and regulations ("JP Foreign Exchange and Foreign Trade Act" and "US Export AdministrationRegulations", etc.). In addition, please do not sell the Products to users who are expected to use it for the above
equipment or companies in its supply chain. If a user who uses module parts and equipment using the Products is acompany suspected of violating human rights, please do not sell the above parts and equipment to that user.

SEIKO NPC CORPORATION
2-9-4, Taito, Taito-ku,
Tokyo 110-0016, Japan
Telephone: +81-3-6747-5300
Facsimile: +81-3-6747-5303
https://www.npc.co.jp/
Email:sales@npc.co.jp

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